University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2022
Views:

111

Pages:

2
Author:

Maverick Martin

Unit 3: Intermolecular Forces and Properties Intermolecular Forces ● Determines the physical properties(g, l, s) of molecular(covalent) liquids and solids ● “Forces”, NOT “bonds” ; WEAKER than ionic/covalent bonds Types of IMFs ● Ion-Induced Dipole: force of attraction between charged ion and nonpolar molecule ● Dipole-induced dipole: force of attraction between polar and nonpolar molecule ● Ion-Dipole Forces (IDF): Between an ion and a partial charge on the end of a polar molecule ● Dipole-Dipole Forces (DDF): Medium force, Between neutral polar molecules, as dipole moment (polarity) increases, DDF increases ● London Dispersion Forces (LDF) (induced dipole-induced dipole): Weak force, between ALL molecules and the ONLY forces between nonpolar molecules, as molar mass increases, LDF increases. This because they have a larger electron cloud which increases the amount of forces in the atom, so they are more polarizable ● Hydrogen bonding forces: Strong force, special type of DDF (stronger than regular DDF), between H (bonded with F/O/N) and F/O/N (of the other molecule) Properties of Solids ● Covalent Network solids: high melting points, insoluble, hard to break or deform, held together by covalent bonds, usually do not conduct electricity as a solid ● Equilibrium Vapor pressure: when the rate of evaporation equals rate of condensation in a closed container Ideal Gas Law ● PV = nRT ● Gas Stoichiometry ○ Molar volume: volume/mole gas at STP; 22.4 L/mol ○ STP: 273 K (0.0°C and 1.0 atm); conditions of an ideal gas ○ Density: DRT/P=Molar Mass ● Dalton’s Law of Partial Pressures: The pressure of a mixture of gases is the sum of the pressures of the different components of the mixture Kinetic Molecular Theory ● Postulates ○ Gases are composed of a large number of particles that behave like hard, spherical objects in a state of constant, random motion. ○ These particles move in a straight line until they collide with another particle or the walls of the container. ○ These particles are much smaller than the distance between particles. Most of the volume of a gas is therefore empty space. There is no force of attraction between gas particles or between the particles and the walls of the container. ○ Collisions between gas particles or collisions with the walls of the container are perfectly elastic. None of the energy of a gas particle is lost when it collides with another particle or with the walls of the container. ○ The average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else. Statements 2,3,6 are untrue in real gases as molecules have finite volume and do exert forces on each other Temperature: measure of the average KE of the particles of matter; can also be thought of as an index of random motions of the particles Diffusion: mixing of gases Effusion: passage of a gas through a tiny orifice into an evacuated chamber ○ ● ● ● ● Solubility ● Solute: the compound that dissolves in solution ● Solvent: the compound that dissolves the Solute ● Miscible = soluble ● Polarity: “Like dissolves Like” → Polar dissolves Polar best, nonpolar with nonpolar. ○ *This does not mean that polar cannot dissolve in nonpolar